Absorbent articles Such as infant diapers, training pants, adult incontinence products, and the like are well known. Such articles have achieved a wide acceptance due to their ability to receive and absorb body exudates.
In general, absorbent articles are formed by multiple webs of material. Such webs generally include a bodyside liner and outer cover on opposing outside surfaces of the absorbent article. An absorbent core generally is located between the bodyside liner and the outer cover. The absorbent core generally has preformed barrier tissue located on a first surface, positioned between the absorbent core and the bodyside liner, and preformed forming tissue located on an opposing second surface, positioned between the absorbent core and the outer cover. The barrier tissue and forming tissue, in combination, completely surround and support the absorbent core.
European Patent Application 0 685 213 A2 published Dec. 6, 1995 discloses depositing fibers onto one surface of absorbent core material to provide a cover. Once the cover of fibers has been deposited and adhered to the absorbent core material, the absorbent core is spirally wound and radially compressed to form a tampon. The fibers at least partially adhere to the surface of the absorbent core material onto which they are deposited. The fibers form an outer cover on the absorbent material.
U.S. Pat. Nos.5,227,107 and 5,409,768 to Dickenson et al disclose forming devices including forming chambers for forming absorbent structures. The Dickenson et al teachings include meltspraying polymer into the forming chamber, along with other fibers, to form an absorbent core. The meltsprayed polymer is mixed with the absorbent fibers and forms an absorbent structure including meltsprayed fibers dispersed internally in the absorbent core.
The present invention relates to methods and systems for making absorbent pads for use in absorbent articles. Opposing surfaces of an absorbent core are supported by a preformed containment layer and a stabilization layer of resin fiber. More particularly, the methods include forming an absorbent core of material in a forming device, applying the pre-formed containment layer against a first surface of the absorbent core, and depositing the stabilization layer comprising resin fiber onto a second surface of the absorbent core. The resin fiber interacts with the absorbent core at the second surface to increase the integrity of the absorbent core. The first containment layer can be applied to the first surface of the absorbent core prior to depositing the stabilization layer onto the absorbent core or after depositing the stabilization layer onto the absorbent core. The method can be devoid of the step of joining a second previously-formed containment layer with material on the second surface of the absorbent core.
In preferred embodiments, resin fibers are deposited onto the second surface of the absorbent core in a random pattern while the fibers are in such condition that properties of the fibers contribute to securement of the fibers to the absorbent core at the second surface. The resin fibers can comprise polyolefins, such as polypropylene.
In some embodiments, the resin fiber is deposited onto the second surface of the absorbent core using a spray nozzle assembly comprising a plurality of nozzles.
The nozzles in the spray nozzle assembly can be arranged in an array extending across the width of the formed absorbent core. The plurality of nozzles can apply the resin fiber across a width, of the absorbent core, of from about 2.5 inches to about 10 inches. Each nozzle preferably includes a single resin aperture exhausting the resin fiber therefrom, and multiple gas apertures directing the resin fiber exhausted therefrom toward the absorbent core, and imparting a random pattern to each such fiber.
In some embodiments, the resin fibers may be deposited onto the second surface in such condition that some of the fibers bond to the absorbent core at the second surface, and to each other at resin fiber crossing points. The resin fiber directed toward the absorbent core can comprise a spray of molten fibers.
Some embodiments of the method include drawing a vacuum on a rotating forming drum of the forming device and thereby assisting in drawing absorbent material toward the drum in the step of forming the absorbent core.
In most embodiments, the absorbent sausage, including the containment layer and the stabilization layer, is severed at spaced locations along the length thereof, to form individual absorbent pads. The absorbent pad is mounted to a bodyside liner, such that the containment layer is located between the bodyside liner and the absorbent pad. An outer cover is mounted to the second surface of the absorbent pad, such that the stabilization layer is located between the absorbent pad and the outer cover.
In some embodiments, the containment layer has first and second edge portions extending outwardly from the first and second opposing edges of the absorbent core. The fibers of the stabilization layer are deposited onto at least part of the first and second edge portions of the containment layer while the fibers are in condition to contribute to securement of the fibers to the containment layer. The fibers become secured to the containment layer, and subsequent cooling of the fibers causes the fibers to lose their securement characteristic, while retaining securement to the containment layer. The containment layer and stabilization layer can entirely encompass the absorbent core.
Another embodiment includes a system for fabricating an absorbent pad comprising a forming device for forming material into an absorbent core, a supply device for supplying a pre-formed containment layer against the first surface of the absorbent core, and spray apparatus for spraying fibers of molten resin onto the second surface of the absorbent core, thereby depositing a stabilization layer onto the second surface such that the resin fibers interact with the absorbent core to increase the integrity of the absorbent core. The absorbent core can comprise a continuous absorbent sausage, the absorbent sausage being a continuous air formed layer of fiber.
In some embodiments, the forming device includes a fiberizer, a forming chamber and a rotatable forming drum, preferably a vacuum forming drum, for forming the absorbent core. The forming device can also include a scarfing roll for shaving material to reduce the thickness of the absorbent core.
In some embodiments, the spray apparatus includes at least one nozzle having a resin aperture for exhausting resin therefrom, and multiple gas apertures for exhausting gas therefrom. The spray apparatus can comprise a nozzle assembly having a plurality of nozzles depositing molten resin onto the second surface of the absorbent core. The plurality of nozzles can define an array of nozzles extending across the width of the formed absorbent core, and can deposit molten resin across a width, of the absorbent core, of from about 2.5 inches to about 10 inches.
In some embodiments, the spray apparatus comprises a meltspray assembly for directing molten resin toward the second surface of the absorbent core as a spray of molten fibers.
In some embodiments, the system includes a vacuum transfer device for receiving the absorbent core from the forming device prior to application of resin to the second surface of the absorbent core. The first surface of the absorbent core and the corresponding containment layer are disposed toward the vacuum transfer device.
In some embodiments, the system includes a trimming device for trimming the containment layer about the absorbent core.
In some embodiments, an absorbent sausage severing device periodically severs the absorbent sausage, including the containment layer and stabilization layer, to form respective absorbent pads.
In preferred embodiments, a main tacker secures each respective absorbent pad between a respective bodyside liner and a respective outer cover, the stabilization layer being adjacent the outer cover.
In typical embodiments, a severing device periodically severs the bodyside liner and the outer cover to thereby form respective absorbent articles.
In some embodiments, first and second portions of the containment layer extend outwardly from first and second opposing edges of the absorbent core. The spray apparatus deposits resin fiber onto at least part of the first and second portions of the containment layer such that the resin fiber interacts with the containment layer, thereby contributing to securement of the resin fiber to the containment layer.
In another embodiment, the system makes an absorbent article comprising a chassis. The chassis is formed of an outer cover, and a bodyside liner mounted to the outer cover and contacting the body of a user. An absorbent core is disposed between the bodyside liner and the outer cover. A pre-formed containment layer is disposed between the bodyside liner and the first surface of the absorbent core. A stabilization layer of resin fiber is disposed between the absorbent core and the outer cover. The stabilization layer interacts with the absorbent core at the second surface to increase the integrity of the absorbent core.
In most embodiments, the stabilization layer comprises fibers deposited on the second surface in a random pattern, properties of the fibers contributing to securement to the second surface. The fibers are typically secured to each other at crossover points. The fibers can comprise polymeric material.
In some embodiments, the containment layer has first and second portions extending outwardly from opposing edges of the absorbent core, the stabilization layer being secured to the containment layer at at least part of the first and second portions, the containment layer and the stabilization layer, in combination, encompassing the absorbent core.
In most embodiments, the containment layer comprises barrier tissue and the stabilization layer comprises a material that is not generally considered to be an adhesive.
In another embodiment a narrow second containment layer is placed along the length of the second surface of the absorbent core. First and second stabilization layers are then spaced on either side of the second containment layer. The stabilization layers can be secured to only the absorbent core, or more nozzles can be selected such that the molten fibers of the first and second stabilization layers can contact the second containment layer and the first containment layer thus securing the containment layers to the absorbent core.